Field of the Invention
The present invention generally relates to a system and method for establishing virtual beams for initial timing synchronization in a satellite communication network. More particularly, the present invention relates to a system and method which establishes virtual beams for initial timing synchronization of remote user terminals in a geostationary satellite based communication network.
Background Information
Communication networks, such as satellite communication networks, employ satellite communication terminals at end-user sites which communicate with one or more satellites in the satellite communication network. As understood in the art, each satellite in the satellite communication network propagates at least one user beam onto a specific region of the earth. For a terminal in the user beam to be able to close the link with the gateway, it's location (latitude,longitude) should be known with precision.
When ordering an installation, a customer provides the installation location which can be as specific as the street address or even the GPS location information, or can be as general as simply the city or town name, or the postal code. Thus, in a typical installation process, the installer at the end-user site can use a location determining device, such as a global positioning system (GPS) device, Google Maps and so on, to determine the location of the satellite terminal if the customer only provided a street address or general information such as city and/or postal code. However, this process of obtaining location information complicates the overall installation process, and thus makes the installation process more time consuming. Furthermore, it is possible that in certain remote locations, such location information is difficult to obtain or unobtainable, which further complicates the process.
To ease this process, a system is proposed where a user beam is subdivided into multiple virtual beams. The center of a virtual beam within the user beam can be used as the terminal location information which is accurate enough for the satellite terminal to close a link with the satellite as long as the satellite terminal is within the virtual beam coverage area as understood in the art. As also understood in the art, the size and locations of the virtual beam (e.g., the number of the virtual beams in a user beam) will be determined by the timing error that is permissible in the system, which can be driven by, for example, customers' requirements, hardware constraints as well as the link budget calculation.